A charge coupled device (CCD) is usually installed in a camera of a camera device, so that the camera device can photograph a color image. The CCD is a special semiconductor device and is used to output luminance of light of different colors to an image processor in an electrical signal manner, so that the image processor finally generates a color image.
FIG. 1 is a schematic diagram of a working principle of a CCD in the prior art. A color filter array (CFA) is disposed in the CCD, and a photosensitive element array is disposed under the color filter array. The color filter array includes filters that are for three colors (red, green, and blue) and that are arranged in a preset sequence. White natural light includes light of seven colors: red, orange, yellow, green, blue, indigo, and purple. The color filter array is used to enable only the red light, the green light, and the blue light in the natural light to pass through the filters and reach the photosensitive element array. The photosensitive element array records an intensity of received light. As shown in FIG. 1, each color filter is corresponding to one photosensitive element. Each photosensitive element is corresponding to one pixel in an image, and a position of each pixel in the image is the same as a position of a corresponding photosensitive element in the photosensitive element array. A green filter in the color filter array is used as an example. Because only green light can pass through the green filter, only green light in an input natural light signal (FIG. 1 shows only the red light, the green light, and the blue light) can reach a photosensitive element. Finally, a real color of a pixel cannot be obtained. In this case, the image processor usually uses a demosaicing (demosaic) algorithm to synthesize the real color of the pixel. Specifically, for a primary color lacked by any pixel, an average value of digital signals of neighboring pixels that have the primary color is used as a digital signal of the primary color of the pixel, to finally obtain the real color of the pixel.
However, each color filter in the color filter array enables light of only one color to pass through and light of another color cannot pass through. Consequently, only some light is input to a photosensitive element, and image noise is relatively high. In addition, a light sampling rate is further reduced, and therefore an image resolution is reduced, that is, light information included in all pixels of an image is reduced. As shown in FIG. 1, only half of photosensitive elements in the photosensitive element array can receive the green light, and finally image quality is affected.